1. Field of the Invention
This invention pertains to cleaning devices, and more particularly to a rotary abrasive cleaning apparatus.
2. Description of the Related Art
In the past, a rotary abrasive cleaning apparatus has been used including a cylindrical drum which had a metal core with rubber layers inside and outside the metal core. Holes were made in the drum, and substantially U-shaped staples were pushed through the holes from the inside toward the outside. Each U-shaped staple was made from a single piece of wire bent into the substantially U-shape and then bent again to form two more bends. Thus, the bending of the wire required two manufacturing steps.
Since the wire was a U-shaped staple, two wire tips had to be aligned with two holes. Further, since the staple was pushed from the inside towards the outside, it was difficult to see the alignment of the wire tips with the holes, and it was difficult to push the staple from the inside toward the outside. The inside diameter of the drum had a minimum limit of the length of the staple, so it was not feasible to make drums with an internal diameter smaller than the length of the staple. The crowns of the staples required considerable space inside the drum, which limited the number of staples and wire tips that a drum could accommodate. For a six-inch diameter rotary cleaning apparatus, the number of axially aligned rows around the circumference of the cleaning apparatus was limited to about 36.
The U-shaped staples were supported by the rubber layer inside the metal core, but since the wires were U-shaped, the support was limited to the amount of rubber between the legs of the staple. As the rotary cleaning apparatus was used, the rubber became worn, and the staples became loose. When the staples became loose, the tips of the wires were not stable which sometimes lead to a tip of a wire being pushed sideways into the path made by another tip, which caused grooving in the surface that was being cleaned. Consequently, the surface was not cleaned uniformly. Although the prior art rotary cleaning apparatus was a good tool for cleaning off rust, scale or paint from a surface being prepared for painting or coating, the apparatus had its limitations. Manufacturing was somewhat expensive; the density of wire tips on the drum was limited; the U-shaped staple was difficult to insert into the drum from the inside toward the outside; and the support for the U-shaped staple was limited since the amount of the staple in contact with the rubber was limited to the crown portion of the staple.